Magnetic properties of Mn-Bi melt-spun ribbons

Mn-Bi melt spun ribbons with the low temperature phase (LIP) of MnBi were produced by melt spinning and subsequent annealing. The as rapidly quenched Mn-Bi melt spun ribbons contained some LIP MnBi phase and exhibited a high coercivity exceeding 8 kOe. Annealing of the melt spun ribbons resulted in an increase in the amount of the LTP MnBi phase. A maximum remanence value 0142 emu/g was achieved in Mn50Bi50 melt-spun ribbon annealed at 673 K for 1 h. High-temperature measurements revealed that the coercivity of the annealed Mn50Bi50 melt-spun ribbon increased with increasing ambient temperature. Although the Mn50Bi50 melt-spun ribbons showed a much smaller coercivity than Nd15Fe77B8 melt-spun ribbon at room temperature, it exhibited a higher coercivity at temperatures of 473 K and higher. Therefore, the magnetic properties of Mn50Bi50 melt-spun ribbon are comparable to those of Nd-Fe-B melt-spun ribbon at an ambient temperature 01 473 K and become superior to those of Nd-Fe-B melt-spun ribbon at 573 K. (C) 2013 Elsevier B.V. All rights reserved.